﻿//  Travel Time Analysis project
//  Copyright (C) 2010 Lukas Kabrt
//
//  This program is free software: you can redistribute it and/or modify
//  it under the terms of the GNU General Public License as published by
//  the Free Software Foundation, either version 3 of the License, or
//  (at your option) any later version.
//
//  This program is distributed in the hope that it will be useful,
//  but WITHOUT ANY WARRANTY; without even the implied warranty of
//  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
//  GNU General Public License for more details.
//
//  You should have received a copy of the GNU General Public License
//  along with this program.  If not, see <http://www.gnu.org/licenses/>.

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;

using LK.GPXUtils;

namespace LK.GPXUtils.Filters {
	/// <summary>
	/// Implements filter that reduces frequncy of the GPS track
	/// </summary>
	public class FrequencyFilter {
		public GPXTrackSegment Filter(TimeSpan minInterval, GPXTrackSegment track) {
			GPXTrackSegment result = new GPXTrackSegment();

			if (track.Nodes.Count == 0)
				return result;

			GPXPoint last = track.Nodes[0];
			result.Nodes.Add(last);

			int index = 1;
			while (index < track.Nodes.Count) {
				if (track.Nodes[index].Time - last.Time >= minInterval) {
					last = track.Nodes[index];
					result.Nodes.Add(last);
				}
				index++;
			}

			if (last.Time != track.Nodes.Last().Time) {
				result.Nodes.Add(track.Nodes.Last());
			}

			return result;
		}
	}
}
